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Helen Raikes, John Love, and Rachel Chazan-Cohen, from the Early Head Start Research and Evaluation team, share evaluation findings and discuss the role of intervention with infants and toddlers in preparing young children for school.¹

Emerging thought in the early childhood field suggests that interventions aimed at infants and toddlers can contribute to putting vulnerable children on the road to school readiness. These ideas are based on what we know about early brain development and the importance of early intervention for improving the odds for low-income children.

The Opportunity of Investing During Infancy
Between birth and age 2 brain growth is fastest and the brain is most flexible. During this period, children acquire language and develop fundamental relationships with caregivers that contribute to lifetime patterns of trust, communication, and emotional regulation. Findings about early development are often used as an argument for educating children between ages 3 and 5. However, many of these findings suggest intervening before age 3, in accord with an oft-stated principle of developmental psychology that says opportunities to alter the course of development are greatest during periods of rapid growth and change.

The conceptual approach of Nobel Laureate Dr. James Heckman brings an economic view to supporting intervention during the earliest years. “Early ability begets further learning,” according to his principle of “dynamic complementarity” (Heckman, 2000). By this principle, children who develop well at earlier ages will elicit interactions and experiences that accelerate development, thereby maximizing the return on early investment.

[School readiness] takes an integrated approach ... because the research clearly tells us health, social-emotional development, and cognitive development are intertwined.

– Joan Lombardi, The Children's Project

Improving the Odds for Low-Income Infants and Toddlers: The Early Head Start Intervention
Early Head Start was launched in 1995 by the Administration for Children and Families in the U.S. Department of Health and Human Services. The program, which now serves more than 63,000 children and families in over 700 American communities, was designed to serve low-income pregnant women, and families with infants and toddlers up to age 3. Early Head Start programs can either be home-based, center-based, or mixed—a combination of the two.

A nationwide impact study was conducted with 3,001 families who applied to 17 Early Head Start programs between July 1996 and September 1998. These families were randomly assigned either to a program group, consisting of those who would participate in Early Head Start, or to a control group, consisting of those who could access all services in their communities except Early Head Start. Interviews with parents and assessments of children's development were conducted when the children were approximately 14, 24, and 36 months old. A comparison of the performance of program group families with those in the control group showed a large number of statistically significant benefits owing to participation in Early Head Start:

  • Early Head Start children scored higher on standardized measures of cognitive and language development at 24 and 36 months, although their performance still trailed the national norms.
  • Early Head Start children showed benefits in social-emotional development. They were rated lower on aggressive behavior problems at 24 and 36 months than those in the control group. Also, at 36 months they were observed to be even more attentive to objects, less negative, and better able to engage their parents during play.
  • Early Head Start parents exhibited increased support for language and learning, were more likely to read daily to their children, and had lower rates of punitive discipline practices when children were 24 and 36 months old.

Several findings are especially noteworthy for policymakers who want to know what types of programs work for what types of families. Programs that fully implemented Head Start's program performance standards and provided a flexible mix of home- and center-based services had the greatest impacts on children's development and family functioning. Among the diverse families served by Early Head Start, impacts were particularly notable for children whose mothers enrolled while still pregnant and whose families faced a moderate number of demographic risks. Early Head Start was particularly effective in enhancing outcomes for African-American families.

Some children in the study developed particularly well across three areas: cognitive development, receptive vocabulary, and sustained attention to objects (see the box below for details). Early Head Start programs offering a mix of home- and center-based services quadrupled a child's chance of performing well on all three outcomes relative to children in the control group.

A Growing Body of Findings on Interventions With Infants and Toddlers
The research on Early Head Start builds on the findings from other demonstration programs for infants and toddlers that show interventions with high-risk infants and toddlers can have long-term effects on children's development. The Carolina Abecedarian Project of the mid-1970s, for example, enrolled 120 high-risk African-American families in four cohorts. That program had large impacts that were sustained into adulthood (Ramey & Campbell, 1991). The Nurse Home Visiting program has also shown sustaining effects in families of first-time mothers (Kitzman et al., 2000). The Early Head Start study, however, is the first to examine the effects of a national intervention for infants and toddlers in a program operated at scale in many different types of communities and with diverse populations. The diverse sample has also created the opportunity to begin to study for whom and under what conditions the program is most effective.

The Early Head Start evaluation illustrates that intervention during the first 3 years of life can positively affect the development of children in low-income families. We have found that it is possible to increase cognitive, linguistic, and social-emotional development over and above the levels seen in the randomly assigned control group. The next step for interventions focused on infants is to continue to conduct rigorous effectiveness studies to learn more about what aspects of interventions are particularly crucial for achieving desired outcomes. The more we know, the better prepared children will be for school from the beginning.

The content of this publication does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. government.

Heckman, J. (2000). Invest in the very young. Chicago: Ounce of Prevention Fund.

Kitzman, H., Olds, D., Sidora, K., Henderson, C., Hanks, C., Cole, R., et al. (2000). Enduring effects of nurse home visitation on maternal life course: A 3-year follow-up of a randomized trial. Journal of the American Medical Association, 283, 1983–1989.

Ramey, C. T., & Campbell, F. (1991). Poverty, early childhood education, and academic competence: The Abecedarian experiment (pp. 190–221). In A. Huston (Ed.), Children in poverty: Child development and public policy. New York: Cambridge University Press.

¹ The Early Head Start Research and Evaluation project was funded by the Administration for Children and Families and conducted under contract to Mathematica Policy Research and Columbia University's National Center for Children and Families, in conjunction with the Early Head Start Research Consortium, consisting of researchers and program directors from 15 universities and 17 research sites. Impact findings were made available in Administration for Children and Families, U.S. Department of Health and Human Services. (2002). Making a difference in the lives of infants and toddlers and their families: The impact of Early Head Start. Washington, DC: Author.


By age 3, how many children are likely to excel on outcome measures in each of the three domains of cognitive development, receptive vocabulary, and sustained attention to objects? To address that question, we identified a subgroup of children who performed well above average on outcome measures in each of these domains. Children in the subgroup scored more than one-half standard deviation above the sample mean on the Bayley1 and PPVT,2 and 6 or better on sustained attention with objects from videotaped mother-child interaction coding.3

Considering each outcome separately, 40% of the program children scored in this range on the Bayley, 36% were above this cutoff on the PPVT, and 30% on sustained attention. However, just a small group did this well on all three measures-only 12%.

Improved Chance of Success Across Multiple Domains
While the program had no statistically significant effect on the percentage of children jointly scoring well on all three measures, large impact effects were seen for some subgroups:

  • In mixed-approach programs, 14% of program children scored in the upper range on all three outcomes compared with just 3.3% of control group children. The effect size for this impact was 36%.
  • Early Head Start significantly increased the percentage of African-American children scoring exceptionally well on all three outcomes, with 11.7% of the program children in this range compared with 1.8% of the control group (an effect size of 33%).

All Kinds of Children Can Be Successful
The Early Head Start children who met this more-demanding cutoff on all three outcomes represent what all programs strive for: children who perform well across multiple domains of development and therefore have the potential to continue high patterns of achievement as they enter preschool, kindergarten, and elementary school. These children averaged 106 on the Bayley (compared with an average of 91.4 for all Early Head Start children) and 100.3 on the PPVT (compared with 83.3 for all Early Head Start children). They came from all 17 sites that participated in the evaluation and represented all racial/ethnic groups.

1 The Bayley Scales of Infant Development measure cognitive and motor development in and assess the behavior of infants from 1 to 42 months of age.
2 The Peabody Picture Vocabulary Test (PPVT-III) measures receptive vocabulary for standard English and screens for verbal ability.
3 Adapted for the national Early Head Start evaluation from Owen, M., Norris, C., Houssan, M., Wetzel, S., Mason, J., & Ohba, C. (1993, September). 24-month mother-child interaction rating scales for the three boxes procedure. Paper presented at the NICHD Study of Early Child Care Research Consortium, Richardson, TX.

Helen H. Raikes, Ph.D.
Visiting Scholar
Society for Research in Child Development

Rachel Chazan-Cohen, Ph.D.
Senior Social Science Analyst

Administration for Children and Families
370 L'Enfant Promenade, SW
Washington, DC 20447
Tel: 202-205-8810

John M. Love, Ph.D.
Senior Fellow
Mathematica Policy Research
P.O. Box 2393
Princeton, NJ 08543-2393
Tel: 541-488-6987

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